Results 6 issues of Vitaly Harisov

Evaluate calc expressions for smaller output: `.foo { width: calc((100px + (20px - 0)) + 10px) }` to `.foo { width: 130px }` `.foo { width: calc((100% + (20px -...

improvement
optimization

See movie: [control-group.mov.zip](https://github.com/bem/bem-components/files/257324/control-group.mov.zip)

### Changes proposed in this pull request - FIX: renderMix: transform nestedMix to the single-item array if it's not an array ### Checklist - [ ] Documentation changed - [...

Currently `postcss-css-variables` generates `undefined` in case it process value with undefined variable. In some cases this is undesirable behavior and undefined variables should be leaved as is without modification. This...

There is no difference for `html-differ` between such files: ```html ``` and ```html ``` This is correct, but it doesn't allow to test different templating engines output.

Please, add to Settings an ability to increase font size for button's letters.